This invention relates to optical transport networks and, more particularly, to optical channel overhead.
It has been determined that it is desirable to provide some latency insensitive, optical channel non-associated optical channel overhead. That is, overhead that does not necessarily have to follow a particular optical channel connection. It has also been determined that is also desirable to provide some optical channel associated optical channel (OCh) overhead (OH). One such arrangement for providing channel associated optical channel overhead is disclosed in co-pending United States Patent application Serial No. (Ballintine-Bonenfant 3-1) noted above and assigned to the assignee of the instant application. The Ballintine-Bonenfant 3-1 application discloses use of a unique digital wrapper arrangement that carries the optical channel associated overhead. Although the digital wrapper functions satisfactorily in many applications, the corresponding associated OCh-OH is typically only available at locations where optical-electronic regenerators are installed. However, it is unlikely that regenerators will be employed at every optical network element in the optical transport network (OTN). Consequently, there was no way to extend OCh maintenance boundaries beyond so-called sub-networks. It is also noted that there are optical network elements that do not terminate the OCh but perform OCh-level maintenance functions. Consequently, there is a need to be able to also carrier OCh-OH information to these optical network elements, where regenerators are usually located.
Problems and limitations of other arrangements for carrying optical channel overhead are overcome by carrying individual optical channel overhead information in a message based channel on an optical supervisory channel. Specifically, this is realized by obtaining performance monitoring, and/or performance measurement, and/or operations, and/or administration, and/or maintenance information, and/or the like for the individual ones of one or more optical channels, formatting the obtained information into a message for each individual optical channel and inserting the resulting message(s) into an optical supervisory channel (OSC) to be transported on the OTN.
In one embodiment of the invention, particular overhead information is formatted into a message and controllably inserted into the optical supervisory channel at a prescribed optical network element to be transported on the OTN.
In another embodiment of the invention, particular overhead information is formatted into a message and controllably inserted into the optical supervisory channel at a prescribed optical network element to be transported on the OTN to a node including the capability to insert the overhead information into channel associated optical channel overhead to be transported to a network element at which it may be removed. Additionally, overhead information transported in channel associated optical channel overhead may be extracted, formatted into a message and inserted in a message based channel in the OSC. The OSC transports the optical channel overhead to a particular node not equipped for associated overhead insertion or removal, where it is extracted form the OSC and used as desired.